Mississippian Subperiod, first major subdivision of the Carboniferous Period, lasting from 358.9 to 323.2 million years ago.
Indeed, the adrenal medulla is an integral part of the sympathetic nervous system, a major subdivision of the autonomic nervous system (see human nervous system).
Selkirk Mountains, major subdivision of the Columbia Mountains, extending for 200 miles (320 km) in a southeasterly arc, mostly in British Columbia, Canada, and just across the U.S. border into northern Idaho and Washington.
Comparative anatomy, the other major subdivision of the field, compares similar body structures in different species of animals in order to understand the adaptive changes they have undergone in the course of evolution.
But despite these films' likability -- their closest reference points include film noir, spaghetti westerns and James Bond -- this major subdivision of Japanese cinema is still overshadowed by the old masters on the one hand and the new practitioners of stylish horror on the other.
The highest points in Romania are reached in the peaks of Mounts Moldoveanu (8,346 feet [2,544 metres]) and Negoiu (8,317 feet [2,535 metres]), both in the Făgăraș Mountains, which, together with the Bucegi, Parâng, and Retezat-Godeanu massifs, form the major subdivision of the region.
Major subdivisions of the Permian Period are identified by extended periods of lowered sea level and by major faunal change.
Other major subdivisions of the system include the Shackleton, Pensacola, Horlick, Queen Alexandra, Britannia, Prince Albert, Dufek, and Admiralty ranges.
Holostean (infraclass Holostei), any member of a group of primitive bony fishes that make up one of the three major subdivisions of the superclass Actinopterygii (ray-finned fishes).
Along with the chondrosteans and the holosteans, they are one of the three major subdivisions of the class Actinopterygii, the most advanced of the bony fishes.
With the rise of the holosteans and teleosts (the other two major subdivisions of the Actinopterygii) during the Mesozoic, the chondrosteans declined.
